Modeling And Experimental Research On The Formation Of The Super-Gravity Vacuum/Low-Pressure Region For Seawater Desalination

Seawater desalination is a promising solution to water scarcity especially for the coastal area. Super-gravity vacuum flash (SGVF) is a novel desalination technique we proposed previously, with a lot of advantages and suitable to be driven by the renewable energy source. The formation of the SGV or low-pressure circumstance is the precondition of this technique, thus the practical means of which are investigated in virtue of the numerical simulations and experimental tests. By analyzing the characteristics of the fluid field necessary for SGV formation, three driving modes of SGVE (SGV evaporator), candidate practical means, are proposed. The simulating results based on the built CFD model show that the dual-wall rotating mode is the best practical mean. The parameter influences are investigated, in good agreements with the theoretical calculations, and also some suggestions for SGVE design and operation are proposed. A test platform is set up to verify that the dual-wall rotating mode is feasible for the formation of the SGV or low-pressure circumstance experimentally. The pressure drop during the formation of the super-gravity low-pressure region is monitored, in good consistence with the simulating and theoretical predictions. At the experimental conditions, the minimal monitored absolute pressure can achieve 8.9 kPa, in the same order as the saturated pressure of water at ambient temperature. The tested energy consumption for driving SGVE is relatively small and would not cause the extra power consumption for the decreasing power requirement of the auxiliary vacuum pump. Furthermore, a novel desalination process, SGV-MD is proposed and analyzed, which is considered more suitable for seawater desalination and renewable energy utilization.